What is a retaining wall?
This is a wall designed specifically to hold soil in place. Retaining walls are often constructed on a boundary or as part of the sub-floor of a building where steep land has been excavated. Backfill and drainage of retaining walls must be constructed and compacted properly to prevent water-logging and damage to the wall, and ensure ground stability.
Retaining wall consent requirements
Significant associated earthworks may require resource consent from New Plymouth District Council (NPDC) and/or Taranaki Regional Council (TRC).
NPDC: For each 100sq.m of site area, up to 20cu.m of material may be filled and/or excavated in any 12 month period. A resource consent will be required where this quantity limitation is exceeded.
TRC: If you are adding fill to the site, please phone TRC on 06-765 7127 to ensure that the fill material and quantity are within the permitted parameters. They will advise you if a resource consent is required.
A building consent is required for retaining walls more than 1.5m high. However, a retaining wall less than 1.5m high will need a building consent if the area above will be subject to additional weight from vehicles or buildings.
Ground conditions may affect the design of the retaining wall - an engineer can assess this. Ground which appears dry on the surface may be considerably wetter deeper down.
Problems with retaining walls
Cracks in your retaining wall?
- Blocked (or a lack of) drain holes.
- A lack of free draining material behind the wall.
- Roots from trees above the wall.
- Overloading of soil above the wall.
- Failure of joints in masonry walls.
Retaining wall bowing or tilting?
- Lack of free draining material behind the wall.
- Wall posts not sufficiently embedded into the ground for the height of the wall.
- Ground excavated in front of the wall.
- Check drainage holes and drains.
- Replace and/or increase the number of supporting parts ensuring depth and footing are adequate.
- Seek advice from an engineer where failure of the wall would be likely to create a danger to people or property.
Fence consent requirements
A building consent is required for fences greater than 2.5m in height. A fence up to 2.5m high does not require a building consent; however, all building work must still comply with the New Zealand Building Code.
Fencing of Swimming Pools Act 1987
Under the Fencing of Swimming Pools Act 1987, if a fence forms part of a swimming pool fence, separate rules and consents apply.
Fences higher than 2m are defined as “buildings” under the District Plan and specific rules apply. You will need to meet these rules.
Location of fences and retaining walls
When constructing a retaining wall or fence near the boundary of a property including the road frontage, make sure the entire structure, including the footings, are within your property (unless it is a shared structure on the boundary as covered by The Fencing Act 1978).
Problems with a tilting fence?
This is commonly caused by:
- Rotting of the base of the timber posts.
- Posts not anchored sufficiently into the ground or tilted by wind.
- Load from a heavy fence too great for the foundations or ground.
- Earth settlement or earth movement.
- Earth is placed against a fence which is not designed to retain soil.
- Replace posts ensuring one-third of post is in the ground.
- Recompact or use concrete around posts.
Tip: Painting a timber fence when it is dry with a light coloured paint will lessen the temperature change, restricting the movement and twisting of the wood.
Problems with your neighbour over a fencing issue
We receive many queries about fencing issues between neighbours. However, we do not advise on shared fencing issues as we regard these as a civil matter.
When building a fence between your property and your neighbour’s property, your respective rights and obligations are set out in The Fencing Act 1978. If you are planning to build on or near the boundary it is courteous to talk to your neighbour first.
Unresolved matters can be taken to the Disputes Tribunal or the District Court. Contact your solicitor or local Citizens Advice Bureau for more information.
Note: If no consent is needed, all building work must still comply with the Building Code.